openssl-dgst, openssl-genpkey: add page (#4879)

pages/common/openssl-genpkey.md

@@ -0,0 +1,16 @@
+# openssl genpkey
+
+> OpenSSL command to generate asymmetric key pairs.
+> More information: <https://www.openssl.org/docs/manmaster/man1/openssl-genpkey.html>.
+
+- Generate an RSA private key of 2048 bits, saving it to a specific file:
+
+`openssl genpkey -algorithm rsa -pkeyopt rsa_keygen_bits:{{2048}} -out {{filename.key}}`
+
+- Generate an elliptic curve private key using the curve `prime256v1`, saving it to a specific file:
+
+`openssl genpkey -algorithm EC -pkeyopt ec_paramgen_curve:{{prime256v1}} -out {{filename.key}}`
+
+- Generate an `ED25519` elliptic curve private key, saving it to a specific file:
+
+`openssl genpkey -algorithm {{ED25519}} -out {{filename.key}}`